Method for controlling a powertrain, a controller, a powertrain and a vehicle

Abstract

A method controls a powertrain having a primary part with an electric motor, a secondary part comprising wheels, a gearbox, and a controller. The gearbox, is configured to, upon receiving an order given by the controller, evolve to a desired configuration, between an engaged configuration in which the primary part and the secondary part are engaged with each other and a disengaged configuration. The method has the steps a) detecting braking intention, b) braking the primary part and controlling the electric motor so that an absolute value of a relative torque between the primary part and the secondary part is lower than a maximal torque, and c) disengaging the primary part from the secondary part.

What is claimed is: 
     
         1 . A method for controlling a powertrain comprising:
 a primary part comprising at least an electric motor,   a secondary part comprising wheels,   a gearbox, and   a controller, wherein the gearbox, is configured to, upon receiving an order given by the controller, evolve to a desired configuration, between an engaged configuration in which the primary part and the secondary part are engaged with each other so as to be secured in rotation with each other and a disengaged configuration in which the primary part and the secondary part are disengaged from each other, enabling rotation of the primary part and the secondary part relative to each other,   wherein the method comprising at least the following steps:   a) detecting an intention to brake the wheels,   b) braking the primary part, and   c) disengaging the primary part from the secondary part.   
     
     
         2 . The method according to  claim 1 , wherein step a) comprises the real time measurement or estimation of a value representative of an angular deceleration of the wheels. 
     
     
         3 . The method according to  claim 1 , wherein the value measured at step a) is an inclination of a braking pedal. 
     
     
         4 . The method according to the  claim 2 , wherein the value measured at step a) is a rotation speed of at least one wheel. 
     
     
         5 . The method according to the  claim 2 , wherein the value measured at step a) is measured by a safety front sensor. 
     
     
         6 . The method according to  claim 1 , wherein during step b), the electric motor is controlled so that an absolute value of a relative torque between the primary part and the secondary part is lower than a maximal torque, the maximal torque being less than 100 Nm. 
     
     
         7 . The method according to  claim 2 , wherein step b) comprises computing a torque applied on the primary part during the braking. 
     
     
         8 . The method according to  claim 1 , wherein the torque applied on the primary part is computed with the following expression: 
       
         
           
             
               
                 Tp 
                 ⁢ 
                 1 
               
               = 
               
                 Ip 
                 ⁢ 
                 1 
                   
                 * 
                 α 
                 ⁢ 
                 1 
               
             
           
         
         where: 
         Tp1 is torque applied on the primary part expressed in Newton meter, 
         α1 is a wanted angular deceleration of the electric motor deduced from the angular deceleration of the wheels expressed in radian per square second, and 
         Ip1 is inertia momentum of the primary part expressed in kilogram square meter. 
       
     
     
         9 . The method according to  claim 1 , wherein step b) lasts less than 200 ms. 
     
     
         10 . The method according to  claim 1 , wherein step c) disengages the gearbox immediately as soon as the torque computed during step b) has been applied by the electric motor. 
     
     
         11 . A non-transitory computer program product comprising a computer readable medium, having thereon a computer program comprising program instructions, the computer program being loadable into a processing unit and adapted to cause execution of a method according to  claim 1 , when the computer program is run by the parameter processing unit. 
     
     
         12 . A computer readable medium having encoded thereon a computer program according to  claim 11 . 
     
     
         13 . A controller comprising a computer readable medium having encoded thereon a computer program comprising program instructions, the computer program being loadable into a-processing unit and adapted to cause execution of a method according to  claim 1 , when the computer program is run by the parameter processing unit. 
     
     
         14 . A powertrain for a vehicle comprising:
 a primary part comprising at least an electric motor,   a secondary part comprising wheels,   a gearbox, and   a controller, wherein the powertrain is configured to, upon receiving an order given by the controller, evolve to a desired configuration, between an engaged configuration in which the primary part and the secondary part are engaged with each other so as to be secured in rotation with each other and a disengaged configuration in which the primary part and the secondary part are disengaged from each other, enabling rotation of the primary part and the secondary part relative to each other,   characterized in that the powertrain is configured to implement the method according to  claim 1 .   
     
     
         15 . A vehicle comprising a powertrain according to  claim 1 .